208 DESCRIPTIVE GEOLOGY. 



Stat.'on, are outcrops of a thin bed of fine-grained, siliceous argillites, wliich 

 are easily recognized on account of their deep vermilion color. They are 

 very fine-grained, splitting into laminse less than half an inch thick, and 

 are full of very distinct impressions of deciduous leaves of the types com- 

 mon in the leaf-beds of the Upper Laramie Cretaceous. They form a 

 well-marked horizon near the upper portion of this series, and are under- 

 laid by sandstones which cany coal seams. The same beds are also found 

 about 10 miles northwest of this point, capped by thin-bedded sandstones. 

 In both losalities, they occupy a nearly horizontal position, having a slight 

 dip to- the westward. -The low, flat ridges, extending north and south from 

 Washakie Station, show no outcrops of any characteristic rocks, being com- 

 posed principally of sands and clays resulting from the decomposition of 

 beds, which might belong to either of these formations. The tops of the 

 ridges are generally capped by thin beds of harder sandstone, which have 

 resisted the action of ei'osion. 



About 1 6 miles, in a direction about east 20° south from Washakie 

 Station, was found, in a shallow valley, an exposure of beds of greenish 

 marls and clays, weathering in peculiar round, smooth, dome-like forms, 

 characteristic of similar beds in the Bridger series. None of the fossil ver- 

 tebrates, which are so characteristic and widely spread through this formation, 

 were found, however, in these beds, and they have, therefore, been included 

 in the color of the Vermillion Creek group, to which horizon their strati- 

 graphical relations most nearly relate them. They have a dip of about 5° to 

 the westward, which would carry them under the red beds of Cathedral Bluffs. 



A few miles southwest from this point, the sandstones of the Laramie 

 group are found, rising at an angle of 15° to 20°, with a strike of north- 

 east and southwest. The upper beds observed were a brown sandstone, 

 underlaid by about 200 feet of friable sandstone, at the base of which 

 are the characteristic bright red, leafy beds, already mentioned. Below 

 these are various sandstones carrying coal seams, and a succession of 

 heavy-bedded sandstones and clays, extending as far south as the Little 

 Muddy, whose section has already been given in the description of Map I. 

 The ridge on the south side of the Little Muddy, at this point, has not 

 been idsited, but on theoretical grounds has been assigned to the Fox Hill 



